This invention is concerned with an adjustable device for artificial limbs, and more particularly with an improved adjustable device by which the gravitational equilibrium of the artificial limb incorporated with this device can be easily adjusted as a user desires.
Many improvements have been made in the construction of artificial limbs, yet there is still much room left to be improvement, particularly in the structure of joints for artificial knees and ankles because of the users' variations in their body dimensions and walking conditions. Generally, both the upper and the lower portions of artificial joints are provided with an adjustable device. As shown in FIG. 1, a typical known adjustable device for an artificial leg includes a sleeve connector B mounted on a positioning pad C round a central tube D of the sleeve connector B and fixed by a plurality of screw bolts A1 to A5, which radially penetrate through the bottom portion of the sleeve connector B, and which have their respective ends abutting against the central tube D of the positioning pad C. For the confort of a user, the sleeve connector B may be positioned as the user desires by first adjusting the screw bolts A1 and A2 located at a bottom side of the sleeve connector B so as to cause the tail ends A11 and A12 of the screw bolts A1 and A2 to disengage with the central tube D, and then tightening the other screw bolts A4 and A5 so as to force the screw bolts A1 and A2 to abut against the central tube D. Consequently, the sleeve connector B is movably inclined a little and its center of gravity is changed accordingly. Apparently, such adjustment is made only for changing the center of gravity of the sleeve connector B. If further adjustment has to be made for satisfying the body equilibrium of the user, the screw bolts A1, A2 and A3 have to be unscrewed and removed from the sleeve connector B for enabling the latter to be disengaged with the positioning pad C, and then the sleeve connector B must be relocated and all the screw bolts A1 through A5 adjusted one by one for properly positioning the sleeve connector B. Finally, the user has to try to walk with the artificial limb to see if it is confortable. If the user finds his center of gravity is not in equilibrium, readjustment has to be made repeatedly.
In addition to the above-mentioned problem, the greater the angular inclination of the sleeve connector B, the less contact the tail ends of some screw bolts (as shown in FIG. 1C) have with the central tube D. Gradually, te tail ends of some screw bolts wear out. As a result, the sleeve connector B may sway slightly, destabilizing the center of gravity and endangering the user's safety as he walks.